Balance staff for a roskopf watch



i 30, 1959 PrTUETEY 3,469,392

BALANCE STAFF FOR A ROSKOPF WATCH Filed Sept. 23, ,1968

PAUL. TUETEY INVENTOR' United States Patent US. Cl. 58-140 3 Claims ABSTRACT OF THE DISCLOSURE A balance staff for a Roskopf watch, provided with a finger performing the functions of the roller jewel of a lever escapement, the balance staff comprising a split collet, driven on the balance staff, the collet having a chambet in which is accommodated the finger, thus ensuring the exact position of the latter, whereas the split of the collet is adapted to cooperate with the guard-pin of the fork.

The present invention relates to a balance staff for a Roskopf watch, provided with a finger performing the functions of the impulse pin or roller jewel of a lever escapement. In general, a notch is milled in such a balance staff for performing the functions of the usual safetyroller, i.e., for cooperating with the guard-pin of the fork.

While the manufacture of the finger is simple (blanking or cutting out), the notch of the balance staff is expensive, since it must be made separately after the profile-turning. In addition, it causes, at the moment of hardening of the balance staff, deformations which render difficult the poising of the watch-balance.

The present invention aims at overcoming these drawbacks. To this end, the balance staff of the invention is characterized by a. split collet, driven on the balance staff, said collet having a chamber in which is accommodated the finger, thus ensuring the exact position of the latter, whereas the split of the collet is adapted to cooperate with the guard-pin of the fork.

The accompanying drawing illustrates, by way of example, an embodiment of the invention.

FIG. 1 is an elevation view, partially in section, of this embodiment, along the line I-I of FIG. 2.

FIG. 2 is a cross-sectional view along the line II-II of FIG. 1.

The balance staff for a Roskopf watch, illustrated in 5 part in the drawing, is denoted generally by the reference numeral 1. As usually, it presents a plurality of portions of different diameters, i.e., the seat 2, to which is riveted the balance (not shown), an intermediary portion 3, the

3,469,392 Patented Sept. 30, 1969 arbor 4 and the pivot-shank 5, followed by the pivot 6 partially illustrated.

A collet 7, split as at 8, distinct from the usual collet (not shown) serving for fixing the inner end of the hairspring, is driven on the balance staff 1, or more precisely on its arbor 4. The collet 7, which may be made of brass, has a height approximately equal to the sum of the heights of the arbor 4 and of the pivot-shank 5, and presents in its lower portion a chamber or recess 9 in which is accommodated the finger 10. The latter is driven on the pivotshank 5 and is oriented in the correct angular position by the collet 7. The split 8 of the collet 7 is indeed just wide enough to form a passage for the arm of the finger 10. As concerns the portion of the split 8 situated above the finger 10, it is adapted to cooperate with the guard-pin (not shown) of the fork.

While I have described and illustrated one embodiment of my invention, it is to be understood that numerous modifications will become readily apparent to those skilled in the art without departing from the spirit of the invention.

What is claimed is:

1. In a balance staff for a Roskopf watch adapted to cooperate with a guard pin of a fork and a finger performing the functions of a roller jewel of a lever escapement, the improvement comprising said staff having an arbor, a split collet driven on said arbor, said collet having an inner chamber in communication with the split, said finger being mounted in said chamber and extending through said split, thus ensuring the exact position of said finger, whereas the split of the collet is adapted to cooperate with the guard pin of the fork.

2. A balance staff as claimed in claim 1 wherein said balance staff has a pivot shank adjacent said arbor, said finger being mounted on said pivot shank, said collet having a height which is approximately equal to the sum of the heights of said arbor and of the pivot shank.

3. A balance staff as claimed in claim 1 wherein said collet chamber is at one end of said collet and surrounds said pivot shank in spaced relation thereto, and said finger comprises a support collar mounted on said pivot shank and housed within said chamber.

References Cited UNITED STATES PATENTS 3,335,562 8/1967 Schneider 58-121 FOREIGN PATENTS 358,360 12/1905 France. 129,930 1/1929 Switzerland. 15 6,802 11/1932 Switzerland.

RICHARD B. WILKINSON, Primary Examiner S. A. WAL, Assistant Examiner 

